Carburetor



Julie 3, 1930. C` F. JOHNSON 1,761,729

vCARBUREVIOR Filed Jan. 14, 1922 Snom/6oz Patented June 3, 1930 UNITED-'STATES CHESTER F. JOHNSON, F DETROIT, MICHIGAN CARBURETOR Application led January 14, 1922. Serial No. 529,210.-

The invention relates to carburetors of the type ordinarily employed in connection with internal combustion engines, and is more particularly concerned with means for controlling the action of the valve whereby air is admitted to the mixingchamber of the carburetor.

The principal object of the invention is to provide means whereby the valve may be so controlled as to supply, at any desired speed of the engine, the amount of air requisite to form the mixture most suitable for that particular speed.

A further object is to eliminate fluttering of the air valve which ordinarily occurs under certain conditions in the operation of valves responsive to suction in the engine intake.

A further object is to render the air valve highly sensitive and accurate in response to slight variations in engine speed, particularly at low or idling speeds. f

A further object is to provide air valve actuating means responsive to temperature changes whereby the quality of the mixture may be correspondingly varied.

Other objects and advantages will appear from the following description taken in connection with the accompanying drawings in which- Figure 1 is a vertical sectional view illustrating one embodiment of the invention,

Figure 2 is a plane view of a portion of the j structure shown in Figure 1,

Figure 3 is a section on line 3 3 of Figure 2,

Figure 4 is an elevation of a portion of anl adjusting element, and

Figure 5 is a fragmentary section, similar to Figure 1, showing a modified form of valve actuating springi Referring to t e drawings, 6 and 7 indicate respectively two sections of a carburetor body which may be suitably/secured together to enclose a mixing chamber. The upper section 6 is formed with a tubular extension 8 having a flange 9 whereby the carburetor may be connected to and supported by the usual intake header or manifold of an internal combustion engine. A throttle valve 10, arranged to be actuated by the usual lever 11, may be mounted in the tubular portie?.y of the section 6. I have found it of advantage to make the tubular. portion 8 of greater diameter than the intake aperture and to provide an abrupt reduction in diameter, as indicated at 12, to correspond to the internal diameter of the intake manifold.

In the floor of the section 7 is anaperture in which is seated astrangle tube 13 in axial alignment with the tube 8. The strangle tube 6o may be secured in any convenient manner, being shown as provided with a flange 14 fitting against the body 7 below the aperture therein and retained by the body section 15 which serves also as a cover for the bowl 16. The body section 15 is formed with a recess 17 surrounding the lower end of the strangle tube to which recess primary air is supplied as through the passages 18. A gasoline feed tube leads from the interior of the bowl 16 70 'and terminates in the nozzle 19 extending within the lower end of the strangle tube. The feed tube may serve also to secure the bowl to the cover or. body 15, screw threadsl 20 being provided for this Apurpose and the tube being extended through the bottom of the bowl and formed exteriorly thereofiwith the head 21 shaped to receive a wrench or like tool. A needle valve 22of usual construction is arranged to regulate iiow through the nozzle and may be adjusted by rotation of the arm 23 secured to the-.lower end of the valve. Fuel may be supplied'to the fuel chamber within bowl 16 from the fuel passage 24, How being controlled in the customary manner b a oat valve 25. Connection is made throng a pipe fitting 26 to a suitable source of supply and a strainer 27 may be mounted in the fuel passage.

The body sections 6 and 7 are laterallv extended to provide a housing for the valve 30 which controls admission of auxiliary air to the mixing chamber through inlet aperture 31. The airvalve may be arran ed to open-either upwardly or downwardly ut is shown as pivotally vsupported on the pin or journal 32 in such position as to swing upwardly to close the aperture 31 and downwardly to admit air under the influence of suction in the engine intake. A spring 33 of 10n materials similar to those of the ordinary bimetallacthermostat is'fixed at one end to the valve and is loosely supported adjacent to the other end on a pin 34 extending transversely through the enlarged head 35 of a plunger 36. The plunger is mounted to slide vertically in an aperture in the base or fioor of the section 7 and the enlarged head is formed with a transverse slot, as shown in Fig. 4, in which the free end of the spring is seated.

The lower end of plunger 36 is guided in a tubular extension 37, which may be a part of the body section 7 and is surrounded by a coiled spring 38 which serves not only to stress the plunger toward its lowest position but also cleans the guide passage and prevents the plunger fromL sticking. Adjustment of the plunger, and thereby of the tension of spring 33, is provided for by lever 38 pivoted at 39 and having one end arranged to contact with the lower end of the plunger. The other end of the lever extends upwardly at 40 in proximit to a fixed abutment 41 on the caruretor ody. threaded hole in the end of lever arm 40 seats against the abutment 41. A spring clip or detent 43 engages the milled or grooved head of screw 42 and retains the screw in adjusted position. By turning the screw inwardly the lever may be caused to swing about the pivot 39 andthe lunger 36 raised thereby increasing the de ection of spring 33 and the force exerted by it tending to close the valve 30.

In starting the engine, particularly in cold weather, it is desirable to maintain the valve 30 in closed position so that the cylinders may be supplied with the rich mixture formed by the commingling of fuel from nozzle 19 with primary air from passages 18. Under such circumstances p ositive closing of the valve may be accomplished by means of a lever 44 fixed upon the pivot pin 39 and suitably connected to actuating means at a point convenient for manual operation. By movement of the lever 44 to the right, (Fig. 1,) the i plunger 36 may be raised until the head 35 engages directly with the lower surface of the valve and thereby prevents the opening of the valve or positively closes it if it should be already open. The direct engagement of the plunger with the valve obviates excessive compression or distortion of the valve actuating spring.

In order to further modify and control the y action of the air valve I provide a buoyant member the buoyant effort of which is exerted preferably in the direction to assist in the closing of the valve. In the form illustrated this member comprises a body 45 of cork or other material lighter than the liquid in which it is placed. A tube 46 which may be formed integrally with the bowl 16 provides a chamber in which the body 45 is loosely enclosed. A passage 47 leads from the A screw 42 mounted in aV fuel chamber to the interior of the tube 46 so that the latter may be normally filled with liquid fuel to a level above the position of the buoyant member. A rod 48, to the lower end of which the body 45 is secured, extends upwardly and is pivotally connected at 49 to the valve 30. The upper end of the tube 46 is closed by a stopper 50 which may be expanded in the tube by a tapered plug 51. Apertures are provided through the plug 51 and the floor of the body section 7 of sufficient size to permitA free movement of the rod 48. The aper tures may be sealed by caps 52, 53, fitting loosely around the rod and lying respectively on the upper end of the plug and the fioor of body section 7. One or more passages 54 connect the space above cap 52 to the exterior air. This atmospheric connection, together with the sealing effect of caps 52, 53, prevents the suction in the mixing chamber from acting upon the fuel in tube 46.

To eliminate fluttering of the air valve I provide a dashpot structure operative to steady the movements of the valve which structure may be conveniently combined with the buoyant device heretofore described. As

shown the dashpot comprises a disk or piston 55 fixed upon the lower end of rod 48 and positioned below the level of passage 4T in order not to affect by its movements the level of fuel in the bowl. The association of the dashpot chamber with the fuel chamber in such manner that the former receives its liquid from the latter is of especial utility inasmuch as it provides for a constant supply of liquid to the dashpot chamber without special care or attention of the operator. The use of a swinging air valve and the connection of the dashpot piston and float to the valve by pivoted means with the elimination of closely titting sliding bearings is also of particular advantage since it promotes free movement of the parts and prevents erratic action due to stickin which is a common cause of complaint 1n connection with the commercial use of sliding valves or rods.

The action of the valve at low or idling speeds is still further modified by the provision of resilient means tending to open the valve and acting thereon during the first part only of the opening movement. In the form shown this means comprises a screw 56 engaging in a screw-threaded aperture in the carburetor body section 6. An axial bore 57 is formed in the screw within which a pin or plunger 58 is slidably mounted. The pin is provided with an enlarged head positioned in a counterbored recess in the head of the screw. A coiled spring 59 mounted in the recess tends to force the pin 58 downwardly. A detent 60 engaging with the milled or grooved head of the screw retains it in adjusted position. A plate 61 fixed to the valve 30 extends beyond the edge of the valve and into the path of ment of the screw 56 the pin may be caused to exert greater or less pressure upon the plate 6l thereby aiding to any desired extent the tendency of the valve to open at idling speeds.

In the modified form illustrated in Fig. 5 the thermostatic spring 33 is replaced by a coiled spring 33. This spring is seated upon the plunger 36 around the enlarged head 35 and engages at the upper end in the seat 62 formed in the lower side of the valve 30'-, The -seat 62 is enlarged as shown at the outer edges in order not to interfere with the free action of the spring. When the plunger 36 is actuated to close the valve positively the head 35 engages directly with the lower surface of the valve, as in the-form previously described, thereby preventing the application of undue pressure to the spring and impairment of its accuracy and sensitiveness.

In the operation of the device thereare live major agencies normally affecting the movements of the air valve. First The iniuence of suction in the intake passages tending to open the valve. Second The weight of the valve itself which tends to open the valve if it be mounted as shown. Third The closing spring 33 yor 33' which exerts a force increasing with the extent of opening. Fourth The buoyant member which exerts a closing force in the position shown, the force remaining substantially constant throughout the v movement lof the valve. Fifth The idle position regulator comprising the spring actuated plunger 58 which exerts an opening influence decreasing with the extent of opening but `operative through a small portion only of the opening movement.

It will be seen that the vweight of the valve is counteractedto a greater or less degree by the action of the buoyant member. The closing spring is thus relieved of a portion of its usual load Vand its tension may be made less than would otherwise be necessary to effect the entire closing of the valve. The closing effect when the valve is closed or only slightly open is then further modified by the opening tendency of the idle regulator with the result that the valve is extremely sensitive to small variations in suction at low or idling speeds.

In other words, disregarding'the weight ofthe valve, its movements within the idling range are controlled by the balance between the action of the buoyant body and the closing springin one direction and of the idle regulator in the other, whereas at higher speeds the opening movement is resisted chiefly by the relatively strong closing spring. The adjustment of the idle regulator may be and preferably is such that the Valve will crack open at even the lowest engine speed thus supplying auxiliary air at any speed.

It will 'be noted furthermore that the adjustment of the closing spring may be varied 4as desired'to affect the proportion of air at high speeds when a leaner mixture is preferable while a practically independent adjustment may be made for low or idling speeds by the counteracting influence of the idle regulator. The invention therefore affords means for obtaining an accurate control over the quality of the fuel'mix-ture through a wide range of requirements not only as to various speeds but to accommodate the peculiarities met with in adapting the carburetor to enginees of diderent constructions.

While the air valve is shown as opening downwardly it will be understood that the invention is not limited to ilse with such arrangement ofvalve but is readily adaptable to other arrangements common in the art. Various othei changes in details of construction and operation may be made without departing from the scope of the invention and therefore I do not wish to be restricted to the specific embodiment herein disclosed except as required by the language of the appended claims in view of the prior art. I claim: t

l. In a carburetor, a mixing chamber, a pivoted air valve, a chamber' for containing liquid, means providing an intermediate space communicating with the external atmosphere between said chambers and passages'connecting each chamber to said space, means operative in said liquid for controlling the movement'of said valve, a rod connecting Isaid means to said valve and passing through said passages, and means for sealing said passages comprising closures fitting said rod above and below said space, and movable to permit said rod to swing.l

` 2. In a carburetor comprising a mixing chamber and means for supplying fuel thereto, a valve adaptedto admit air to said chamber, a buoyant member normally submerged in liquid and connected to said valve, a dashpot associated with the valve to steady the movement thereof, resilient means tending to close the valve, and resilient means tending to open the valve and operative thereupon during the first part only of ythe Qpening movement.

3. In a carburetor comprising a mixing chamber and means for supplying fuel thereto, a valve adapted to admit air to said chamber, a spring operative to move said Valve to- Ward closed position, said spring formed of thermostatic metal and adapted to reduce the tendency to close the valve as the temperature rises, means for adjusting the tension of said spring and means operating through said adjusting means to close the valve positively.

4. In a carburetor comprising a mixing chamber and means for supplying fuel thereto, an air valve, a buoyant member normally submerged in liquid and connected to said valve, resilient means operative to move said valve toward closed position and resilient means tending to move said valve toward open position and acting upon the valve during the first part only of its opening movement.

5. In a carburetor, a mixing chamber, means for supplying fuel thereto, a valve adapted to admit air to said chamber under the iniuence of suction therein, a spring adapted to resist opening movement of said valve, a plunger providing an abutment for said spring, means for adjusting said plunger to vary the initial tension of said spring, said plunger having a part adapted to engage said valve and positively close the same, and means for actuating said plunger to close said valve positively.

6. In a carburetor, a mixing chamber, means for supplying fuel thereto, a valve adapted to admit air to said chamber under the influence of suction therein, a Yspring adapted to resist opening Lmovement of said valve, a plunger providing an abutment for said spring, manually operable means for moving said plunger to hold said valve closed to provide a rich mixture, resilient means for returning the plunger to normal position and means for adjusting the normal position of said lunger.

7. n a carburetor, a mixing chamber, means for supplying fuel thereto, a valve adapted to admit air to said chamber under the influence of suction therein, a spring adapted to resist opening movement of Said valve, a plunger providing an abutment for said spring, means .for moving said plunger in a direction to increase the resistance to opening movement of the valve exerted by said spring to provide a rich mixture, resilient means for returning the lunger to normal position and means for adjusting the normal position of said plunger.

In testimony whereof I aiix my signature.

CHESTER F. JOHNSON, 

